1 FIELD OF THE INVENTION
The invention concerns a window with openable casement and an insulating glass pane made out of a colorless glass pane and an absorption pane, selective for solar radiation.
Due to the above-mentioned glass pane combination, insulating glass elements of this type have, depending on their positioning relative to the radiation source, different transmission characteristics for the transmission of solar radiant energy. Depending on the position of the absorption pane with respect to the radiation source, such an insulating glass element can therefore be utilized in the summer as a sunshade element having a low radiant energy transmission and in the winter as solar collector element having a high solar radiant energy transmission. By designing such insulating glass panes so that they are reversible, i.e. so that the insulating glass pane can be directed, as desired, with one or its other face towards the outside of a room, the costs for air conditioning of rooms equipped with such insulating glass panes can be reduced both in winter and in summer.
The absorption pane of the insulating glass element, which is designed to be selective with regard to the invisible range of the solar radiation and which points outwards in the summer position, absorbs the invisible parts of the solar energy spectrum and converts them to thermal energy which is dissipated to the external atmosphere by convection and radiation. This effect is aided by the application of a coating, reducing the emission of thermal radiation of long wavelength, on the inner surface of the absorption pane. The visible solar radiation portion penetrates both the absorption pane and colorless glass pane of the insulating glass element which is arranged behind the former and is transparent to the complete radiation spectrum.
By a 180.degree. rotation of the insulating glass element, the colorless glass pane points, in the winter position, in the direction of the radiation source. The incident solar radiation penetrates this pane almost without any loss and strikes the absorption pane which is now turned towards the room. Both the penetrating visible portions as well as the portions of the solar radiation spectrum absorbed and converted to thermal energy by this pane benefit the room since the emission reducing coating of the absorption pane, now turned to the outside, prevents the dissipation of heat to the outside.
An additional effect heightens the energy gain on the side of the room. Already at low solar radiation intensity, the absorption pane turned towards the room is heated to room temperature. During this temperature alignment, the pane takes on a thermal resistance value which is quasi infinite with respect to the air of the room. The effective k value of the insulating glass element is then k=0.